[ctool]

I bought some GE Silicone II Sealant for windows from Home Depot.  I used a little, and put the cap on.  Apparently, the cap is not airtight, and something has evaporated out of the mixture.  Now, when I try to use it, the stuff no longer hardens up.  It just stays gooey.   So I was wondering if there is something that I could mix into it that would cause it to harden up, like its supposed to.  Any Ideas?  I don't want to have to throw away an almost full bottle.

Thanks

[Borek]

Strange, as far as I know silicone polymerizes in the presence of water (small amounts always present in the air are enough). In my experience if the cap is not airtight silicone hardens near the hole which renders tube useless. No idea what may have happened in your case.